#pragma warning(disable:4996)
#include<stdio.h>

int main() {
    int a, b, c;
    double T;
    scanf("%d %d %d", &a, &b, &c);
    T = a * 0.3 + b * 0.2 + c * 0.5;
    printf("%.1f\n", T);
	return 0;
}